In shell-secreting molluscs, age and growth rate of individuals and hence their performance can normally be measured using growth lines that are deposited in the shell throughout their lives. An annual periodicity of growth line formation of the warm-water limpet Patella depressa was established using marked and recaptured individuals from north Wales, UK. Length at age from suitably prepared shell sections was determined in limpets from non-range-edge populations and at two range edges, where different demographic attributes have been recorded. Individuals collected from their poleward range-edge in north Wales were older when compared with individuals at their range-edge in southern England. Shells collected from southern England were characterized by rapid growth with most individuals reaching >30 mm in maximum length by the fourth or fifth year, contrasting with those from north Wales, where most shells only reached this size at 7–10 years of age. Von Bertalanffy growth coefficients (K-values) were negatively related to P. depressa density, showing faster growth in lower total densities of both P. depressa and Patella vulgata combined. Higher intra-specific effects on K-values were found in P. depressa compared with its congener P. vulgata, with stronger effects in north Wales than in southern England. These results confirm differences in population patterns and individual traits between the two leading edges of P. depressa. Understanding annual growth in P. depressa over large scales could help to disentangle the processes determining differences in shell growth and age structure seen at the two range edges of this limpet species.

中文翻译：

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壳的生长和年龄由南部温水帽贝Patella depressa在其极地地理边界处的年线确定

在分泌壳的软体动物中，个体的年龄和生长速度以及它们的性能通常可以使用在其一生中沉积在壳中的生长线来测量。温水帽贝生长线形成的年周期髌骨下陷是使用来自英国北威尔士的标记和重新捕获的个人建立的。从非范围边缘种群和两个范围边缘的帽贝中确定适当制备的贝壳部分的年龄长度，其中记录了不同的人口统计属性。从威尔士北部极地范围边缘收集的个体与英格兰南部范围边缘的个体相比年龄更大。从英格兰南部收集的贝壳的特点是生长迅速，大多数个体在第四年或第五年的最大长度达到 > 30 毫米，而来自威尔士北部的贝壳则在 7-10 岁时才达到这个大小。Von Bertalanffy 增长系数（K 值）与P. depressa密度，在较低的总密度中显示出较快的增长P. depressa和普通髌骨结合。更高的特异性内效应ķ-值被发现在P. depressa与其同类相比P. vulgata，在威尔士北部的影响比在英格兰南部更强。这些结果证实了两个前沿之间的种群模式和个体特征的差异P. depressa. 了解年增长率P. depressa在大尺度上可以帮助解开决定在这个帽贝物种的两个范围边缘看到的贝壳生长和年龄结构差异的过程。